Astec Standard Power Europe
Astec House, Waterfront Business
Park, Merry Hill, Dudley
DY5 1LX, UK
Tel: 01384 842211
Fax: 01384 843355
Astec Germany GmbH
Robert-Heil-Str. 8
36251 Bad Hersfeld
Tel: 06621-5057-0
Fax: 06621-5057-20
Astec France
Les Arcades
424, la Closerie Mont d’Est
93194 Noisy Le Grand
Tel: (1) 43 05 86 80
Fax: (1) 43 04 60 33
Application Note Number 12
Product:
Astec MVP Range of modular power supplies.
Application Overview: Wide range remote programming of MVP single output
modules.
Originator: Paul Haycock
Location: ASP UK
Date: 11-11-97
Schematic
Figure 1
Figure 2
Figure 3
Page 1 of 2
Application Note Number 12
Description
The Astec MVP range of switched mode power supplies are designed to be of a modular
construction, enabling ‘tailor made’ solutions for customer applications.
The single output modules have factory adjustable output voltages ranging from 2-60vdc
and include many features as standard. One of these features, the Remote Margining,
enables the user to adjust the nominal o/p voltage of each module remotely by +/- 4-6%
in addition to the +/- 10% adjustment via the pot.
If this function is not required the V Prog (pin J1-2) is left open circuit and the output
voltage will remain at the pre-set nominal. In this configuration the voltage on J1-2 is fixed
at approximately 1.5V. However, connecting pin J1-2 directly to either J1-3 or J1-4 will
increase or decrease the voltage on J1-2, to approximately 3V or 0V. This will change the
nominal o/p voltage by +/- 5% respectively. Additionally, connecting a 10K potentiometer
across J1-3 and J1-4, see fig 1, will allow a linear adjustment of the nominal o/p voltage by
approximately +/-5%, see Fig 2.
The output can be further reduced below the -5% point, by increasing the negative voltage
applied to the V Prog (J1-2) pin. The following graph shows the range of adjustment
possible by remote margining, from 110% to 10% of the nominal output voltage. However,
when the voltage is reduced the current limit of the module is also reduced, limiting the
maximum power available. The graph shows the power available for the modified output
voltage. Additionally, noise and ripple measurements of the o/p are unaffected by the
remote voltage margining function.
The negative voltage required by pin J1-2 can be simply obtained by using an additional
MVP module, see Fig 3. Due to the isolated output the connection between modules is
straightforward. The following block diagram shows the general layout. The voltage control
block could be a simple potentiometer or even a DA converter driven by a computer.
R e m o te M a rg in in g o f s in g le o u tp u t
M V P m o d u le s .
120
Output Voltage / Power (%)
100
80
60
40
O /P V o lta g e
20
O /P P o w e r
0
-2 5
-2 0
-1 5
-1 0
-5
0
5
V o lta g e p ro g ra m (J 1 -2 / J 1 -4 )
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